I've got 2 sets of bilge pumps in a lagoon 440. One set that is automatic (and working fine) and one that is manual and not functioning.

I've traced the problem to a faulty ground on the pump circuits and I can use another set of wires to work around the problem, but I can't figure out where the ground wire might be broken. The problem is affecting BOTH hulls, so I figure it is a common attachment point.

In the electrical cabinet there are 3 bundles of ground wires all of which appear to be solidly connected (and if they weren't I'd expect a lot more things to not be working) but I don't really know where else to look for these grounds which I think are 12 gauge. The pumps are on separate switches and I've only checked the problem on the starboard side, but using a separate power cable proves the problem is NOT in the pump but in the wiring on both sides.

I'm going to try my tone generator on the problem tomorrow to see if I can find out anything else. I was wondering if there was some separate ground bus somewhere outside the electrical cabinet next to the back door of the salon.

QUOTE "but I can't figure out where the ground wire might be broken." UNQUOTE.

If I understand you correctly why don't you do a binary search?

Tap into the earth wire in the middle to see which half is broken by using your multi-meter.

Then tap midway into the broken half to see which half is broken.

Then tap midway into the broken half to see which half is broken.

Then tap midway into the broken half to see which half is broken.

Then tap midway into the broken half to see which half is broken.

If the cable is 10 ft you'll isolate the break to 5 ft after the first tap, then you'll isolate it to 2'6", then you'll isolate it to 1'3". After the 4th tap you will know within 7Ĺ inches. (After a 5th tap - 3ĺ inches. After a sixth tap - 1⅞ inches)

I solved it already. There is a switch in the electrical pedestal and one at the wheel. They are wired in series so both switches have to be on for the pump to work. There is also a relay involved as well. The tone generator helped me figure this out.

That's an excellent question and one I don't speak french well enough to ask :-) . Not that Lagoon would answer anyway. I had assumed the same and if I had not had a tone generator I would never have guessed it was wired this way. Also I don't understand the 20Amp Relay for an 11 amp load that is behind a breaker in the panel... But at least now I know how the boat is wired.